Storage Tank Or Return Temperature (B32); Measuring Variable; Types Of Sensors; Handling Faults - Siemens RVD230 Basic Documentation

Siemens Building Technologies
HVAC Products
4.7 D.h.w. storage tank or return temperature
(B32)
4.7.1

Measuring variable

Depending on the type of plant, input B32 is used for making the following temperature
acquisitions:
• secondary return temperature in the d.h.w. circuit (plant types x–4)
• storage tank temperature (other plant types)
4.7.2

Types of sensors

The type of sensor is the QAE22... immersion sensor with a sensing element LG-
Ni 1000.
Thermostats cannot be used.
4.7.3

Handling faults

• When used as a storage tank temperature sensor:
In the event of a short-circuit or open-circuit, the controller first attempts to use the
second sensor. If no second sensor is available, an error message will be generated
• When used as a secondary return temperature sensor:
If there is a short-circuit in the measuring circuit, an appropriate error message will be
generated
4.8

Primary return temperature (B7, B71 and B72)

4.8.1

Measurement

Depending on the type of plant, the primary return temperature is fed to input B7, B71
or B72.
This measured value is required for maximum limitation of the primary return tempera-
ture and for limiting the temperature differential.
With plant types 2–x, 3–x, 6–x, 7–x, 8–4 and x–0, the primary return temperature at B7
is passed on via LPB; with plant types 0–x, it is measured value B72.
4.8.2 Types of sensors
The following types of sensors can be used:
• All types of sensors from Siemens with a sensing element LG-Ni 1000. Suited for
d.h.w. applications is immersion temperature sensor QAE2... . Its range of use is
0...130 °C
• Commercially available immersion temperature sensors with a sensing element Pt 500
The sensing range of all types is 0...140 °C; but the Pt sensors are suited for medium
temperatures up to 180 °C.
The controller automatically identifies the type of sensor used.
4.8.3 Handling faults
In the event of a faulty primary return temperature sensor (short-circuit or open-circuit),
an error message will be generated when maximum limitation of the primary return
Basic Documentation RVD230
4 Acquisition of measured values
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CE1P2383en
27.05.2004